[PATCH v3 00/10] About the SLC/MLC

[Ezequiel Garcia]

Hi Huang,

On Mon, Aug 26, 2013 at 11:30:22PM -0400, Huang Shijie wrote:
> On Mon, Aug 26, 2013 at 02:41:53PM +0200, Thomas Petazzoni wrote:
> > 
> > On Mon, 26 Aug 2013 17:36:38 +0800, Huang Shijie wrote:
> > > In current mtd code, the MTD_NANDFLASH is used to represent both the
> > > SLC nand MLC(including the TLC). But we already have the MTD_MLCNANDFLASH
> > > to stand for the MLC. What is worse is that the JFFS2 may run on the MLC
> > > nand with current code. For the reason of READ/WRITE disturbance, the JFFS2
> > > should runs on the SLC only,
> > 
> > Pardon the probably very silly question, but would you mind giving more
> > details about why JFFS2 is not appropriate on MLC flashes? Is there
> > anything that UBI/UBIFS does that JFFS2 isn't doing to take into
> > account read/write disturbance?
> I try to explain it.
> 
> For the UBIFS, it will writes the page(including the oob) only one time;
> but for jffs2, it may writes the page(including the oob) twice, one for the
> marker, one for the real data. 
> 

It seems I overlooked this when I first read it.

Do you mean that JFFS2 will write twice: one write to the spare region,
one write in the data region, with no erase between those two?

I've looked at the JFFS2 code, but it's not trivial to follow :)
-- 
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com